import java.util.Scanner;
import java.text.DecimalFormat;
public class pp34
{
   public static void main (String[] args)
    {
       int x1,x2,y1,y2;
       double D,C; 
        Scanner scan = new Scanner(System.in);
        DecimalFormat tlm = new DecimalFormat ("0.###");

        System.out.println ("Enter the X1: ");
        x1 = scan.nextInt();
        System.out.println ("Enter the X2: ");
        x2 = scan.nextInt();
        System.out.println ("Enter the Y1: ");
        y1 = scan.nextInt();
        System.out.println ("Enter the Y2: ");
        y2  = scan.nextInt();

        C = Math.pow((x1 - x2),2) + Math.pow((y1 - y2),2);
        D = Math.sqrt(C);
        System.out.println ("Answer: " + tlm.format(D));
    }
}

        
